Experiments similar to those of Willis were performed under slightly better controlled conditions of strength of materials and pressure. The relationship between stratigraphic thickness and deformation was compared graphically with data obtained by direct field observation. A surprisingly close agreement was found.
The conclusion is drawn that apparent thickening of anticlines and synclines and thinning of limbs has been accomplished mainly by differential compaction in the early stages of deformation; recrystallization where present became important in late folding.
The writer believes that adjustment has been accomplished in the folds under consideration by shear-flow rather than by recrystallization. He presents evidence to show that contrary to a widely held view shear-flow is not a phenomenon of great depth but may occur within 7500 feet of the surface of the earth.
Porosity and crushing strength were compared graphically with deformation, and the conclusion drawn was that radial compression on the limbs has acted to modify both.